Ординатура / Офтальмология / Английские материалы / Corneal Endothelial Transplant (DSAEK, DMEK & DLEK)_John_2010

Figure 28-8: Single slit-incision to drain localized interface fluid collection.

•Recognizing and correcting any impediments to unfolding of the donor corneal disk within the recipient anterior chamber (e.g. vitreous band through pupil to cornea, vitreous in the anterior chamber, very shallow, crowded anterior chamber, extensive anterior synechiae)

•Staining the donor surface with trypan blue (Vision Blue) to identify the stromal surface from the donor endothelial surface (See also Chapter 32, Use of Dyes in DSAEK and DLEK)

•Use of surgical slit-lamp (See also Chapter 10, Role of Surgical Slit-lamp in Endothelial Transplantation and Anterior Segment Surgery)

•Introducing donor corneal disk with the endothelial side facing the anterior iris surface (e.g. Busin glide, sheetsglide, suture-pulling techniques, injecting device delivering donor disk with the endothelial side down). Do take into consideration the amount of endothelial cell loss during endothelium-down delivery of donor corneal disk into the recipient anterior chamber.

Disk Detachment during Unfolding

Re-attach the disk with additional air.

Dropped Disk into Vitreous Cavity

Dropped disk in most instances can be prevented if proper preoperative assessment is made prior to surgery. Increased risk for dropping the donor disk into the vitreous cavity includes the following:

•Aphakic eyes

•Large complete iridectomy without any posterior support such as a PC IOL blocking most of the iris opening

•Aniridia.

If the donor corneal disk is accidentally dropped into

the vitreous cavity, avoid deep vitreous cavity “fishing.” Trying to grab a dropped disk can cause additional ocular tissue damage and possible permanent visual loss. Close the eye and refer the patient to a vitreoretinal surgeon to surgically remove the dropped donor corneal disk.

Postoperative Complications

1.Disk detachment

2.Macro-folds

3.Interface blood

4.Epithelial ingrowth

5.Graft rejection

6.Failed graft

7.Infection.

Disk Detachment

Disk detachment in the immediate postoperative period may occur following DSAEK surgery. This is usually detected on the day following surgery. However, late disk detachment can also occur. Disk detachment may be a result of the patient rubbing the eye following DSAEK, or the surgical techniques used during surgery may not have been sufficient for proper donor disk adherence to the inner surface of the recipient cornea.

When the donor disk is detached it usually rests inferiorly with the edge of the disk being captured within the inferior aspect of the anterior chamber angle. Disk reattachment is a relatively simple surgical procedure (Figures 28-9 to 28-12) and may be done on the next day or within about 7 to 10 days following the initial surgery. Any delay past 10 days may result in anterior synechiae formation and risk of disk damage and difficulty with the removal and re-attachment surgery.

The re-attachment (Figures 28-9 to 28-12) is done under topical anesthesia, namely, 2% lidocaine jelly and monitored anesthesia care (MAC). A 30-gauge cannula is placed in the region between the detached disk and the anterior iris surface and filtered-air is injected to raise and attach the donor disk to the recipient corneal stroma. The disk is centered using a reverse Sinskey hook. Selective slit incision may be made to drain any localized fluid collection. The epithelium may be removed to enhance the view of the donor disk, the interface and the anterior chamber.

Figure 28-9: Temporal approach—30-gauge cannula is inserted through a stab incision and the tip of the cannula is placed between the detached donor corneal disk and the anterior iris surface.

Figure 28-10: Air bubble in the anterior chamber raises the detached disk and brings it into contact with the recipient inner corneal stroma.

Figure 28-11: The donor corneal disk is moved to proper centration using a reverse Sinskey hook. The epithelium is removed to increase the visualization of the donor corneal disk and the donor-recipient interface.

Macro-folds

Macro-folds may rarely be seen following DSAEK surgery and may occasionally persist (Figures 28-13 to 28-15). If postoperative follow-up shows continued wound remodeling and decrease in the degree of the donor disk folds then one can continue to watch without any surgical intervention. If the patient is very symptomatic from these folds and if there is no improvement over time, then a disk exchange may be considered.

Interface Blood

Interface blood is to be avoided if possible. Meticulous hemostasis before entering the anterior chamber via the temporal wound is essential. If there is surface blood this can enter into the eye and get trapped in the donor-recipient interface. Interface blood can last for a long time and may contribute to visual degradation, visual symptoms, and interface inflammation.

Epithelial Ingrowth

This is a rare complication of the “vent” incisions that is made to drain any interface fluid and enhance donor corneal adherence to the recipient cornea. Management is similar

to any epithelial ingrowth within the cornea. Watch for progression of the epithelial island, any overlying corneal melt. Surgical intervention will be necessary if the above mentioned complications occur.

Graft Rejection

Since DSAEK involves endothelial transplantation from a donor cornea, endothelial graft rejection can occur (Figure 28-16). The treatment of graft rejection is similar to endothelial graft rejection following a penetrating keratoplasty, namely, frequent topical corticosteroid drops and cycloplegia.

Failed Graft

Graft rejection not resolved with medical treatment can result in a failed graft following DSAEK, DMEK, and DLEK procedures. Figure 28-17 displays the ultra-structural findings in a case of failed DLEK graft.

In DSAEK, a disk exchange may be the preferred choice over a full-thickness penetrating keratoplasty. Figures 28-18 to 28-27 display the surgical steps in disk exchange following a failed DSAEK graft, after a failed penetrating keratoplasty (PKP).